visualisation

As a follow-up to #11540, we would like to add metadata to as many examples as possible. This will not only make the examples more usable as they are right now, but it will also open up new possibilities to search for and crosslink examples.

For the purpose of this issue, 'standalone examples' are all .py files in these folders in this repository:

• examples/plotting/file
• `examples/mode

I don't think this is a duplicate ticket, even though it's quite an obvious feature after that cat demo at SciPy2018.

The code that selects and renders the different geos is here in the THREE.js code
https://github.com/maartenbreddels/ipyvolume/blob/master/js/src/scatter.js#L57

I don't know quite where/how to inject the mesh definition compatible with the data file of this form, but i

📚 Documentation

A user suggested earlier today that it's not easy to discover the gallery in the docs because the userguide doesn't cross-reference to it at suitable points. This seems like an easy way to make the docs more useful, without mu